The invention relates to the transmission of data, and particularly to the transmission of data relating to longwall mining systems.
The longwall method of mining is well known, and involves the use of a mineral cutting machine which travels back and forth across a wall of mineral. The cutting machine is mounted on a conveyor extending along the length of the wall, and as the cutting machine removes mineral from the wall, the mineral is conveyed to the end of the wall by the conveyor.
During the mining sequence, the exposed mine roof is supported by a row of hydraulic mine roof supports, each support being connected to the conveyor by an advancing ram. Once a new web of mineral has been removed, the conveyor must be advanced to a new position adjacent the newly cut face, and the mine roof supports must then follow to a new position adjacent to the conveyor.
This movement is carried out in stages. The conveyor is sufficiently flexible to perform a snaking movement along its length, and once the mineral cutting machine has moved past a given section of conveyor by a distance which is not less than the length of the snaked portion, that section is pushed forward by extending the advancing rams of the associated supports. The supports, each of which comprises a base, a roof engaging canopy, and hydraulic support legs, can be selectively advanced sequentially by lowering a given support from the roof, retracting its advancing ram to pull the support close to the conveyor again, and then resetting the support to the roof.
As mining techniques are becoming more and more sophisticated, there is a greater requirement for the degree of control to be exercised over the movement of the mining machine, the conveyor, and the supports, and in turn there is a greater requirement to receive data from these components concerning the manner in which they are operating, their position with respect to one another, and other parameters.